1. Technical Field of the Invention
The present invention relates generally to gypsum board and methods for making gypsum board. More specifically, the present invention relates to improved gypsum board possessing antifungal properties and improved methods of making the same.
2. Description of Related Art
Gypsum board, which is sold as wallboard and drywall, is a common building material used in various applications including interior walls, partitions and ceiling construction. Commercial gypsum board products are popular for a variety of reasons. They are durable, economical and fire-retardant. In addition, these boards provide excellent compressive-strength properties and a relatively low density. Finally, they are easily decorated and are therefore attractive as surfacing materials, especially for interior construction.
One fundamental limitation of traditional gypsum board products is their susceptibility to moisture absorption in damp environments. To minimize this problem, gypsum board is normally used in interior construction where exposure to moisture is limited. Unfortunately, products used in interior construction sometimes encounter water due to seepage, leaky roofs or pipes, flooding, condensation, and the like, arising out of construction defects or other events unrelated to the manufacture of the gypsum board. Thus, a number of mechanisms result in the exposure of gypsum board products to moisture. Once exposed to moisture, traditional gypsum board products are susceptible to fungal growth.
In patent application publication numbers US2003/0035981 and US2003/0031898, there are disclosed antifungal gypsum boards in which monomeric antifungal agents are included in components of wallboard materials. Due to the monomeric nature of the antifungal agents, such as the preferred antifungal agents of those disclosures, cetyl pyridinium chloride, those published patent applications discuss the inclusion of binders, retention aids, encapsulants and the like, for retaining the monomeric antifungal agents in association with the gypsum board components. The present invention provides an improved antifungal gypsum board by disclosing polymeric compounds which are antifungal and which therefore have enhanced antifungal efficacy and retention in the gypsum board components. We have also found that polymeric quaternary amines are significantly more antimicrobial than are monomeric quaternary amines.
There is an ongoing need for gypsum board products that offer reduced susceptibility to fungal growth without compromising their beneficial properties. In addition, there is an ongoing need for commercially viable manufacturing methods for such products. The present invention solves these problems by using an improved antifungal agent that effectively inhibits fungal growth, is compatible with gypsum board materials, and can be incorporated into a cost-effective and commercially-viable manufacturing process.